Q&A with Stephen P. Radzevich Ph.D.

You have written a book titled, Theory of Gearing: Kinematics, Geometry, and Synthesis. What does the book discuss?

This book systematically presents and develops a scientific theory of gearing, specifically for those involved in gear design, analysis, and manufacture. I begin with a few simple postulates that form the foundation of the theory of gearing. The postulated concepts are limited to just two entities, namely to (a) rotation vectors of the driving shaft and of the driven shaft, and to (b) torque on the driving shaft. The rest of the design parameters of an optimal gear pair are derived from the information already mentioned.

Tell me a little more about yourself. The press release for the book says you are a gear expert writing for gear experts. Please explain.

I am a Professor of Mechanical Engineering, and a Professor of Manufacturing Engineering. I received the M.Sc. (1976), Ph.D. (1982), and the Dr. (Eng) Sc. (1991) – all in mechanical engineering. I have extensive industrial experience in gear design and manufacture and have developed numerous software packages dealing with CAD and CAM of precise gear finishing for a variety of industrial sponsors. My main research interest is Kinematic Geometry of Surface Generation, particularly with the focus on precision gear design, high power density gear trains, torque share in multi-flow gear trains, design of special purpose gear cutting/finishing tools, design and machining (finishing) of precision gears for low-noise/noiseless transmissions of cars, light trucks etc.

I’ve spent more than 35 years developing software, hardware and other processes for gear design optimization. In addition to industry work, I train engineering students at universities and gear engineers in companies.

What are the chapter topics for this book?

Chapter One is on Synthesis, including kinematics of gear pairs; geometry of gear tooth flanks with a preliminary discussion, geometry of contact tooth flanks of two gears in mesh, and concept of synthesis of a gear pair with prescribed performance. Chapter two is on the ideal gearing: parallel-axis gearing, which includes involute gearing, noninvolute gearing, high-conforming parallel-axis gearing, and the synthesis of optimal parallel-axis gearing.

Chapter Three is ideal gearing: intersected-axis gearing and discusses geometrically accurate intersected-axis gear pairs and high-conforming intersected-axis gearing. Next we discuss crossed axis gearing, geometrically accurate two-degree of freedom gearing, real gears and their application: gear trains and real gears and their application: principal features of power transmission and loading of the gear teeth.

The main reason for writing the book is absence of clear understanding of kinematics of geometry of gearing in the previously published booksbooks published earlier. My book provides the reader with a systematic and comprehensive explanation of gearing of any and of all kinds, regardless of how complex a particular gear pair is. This has never been done before.

What are some of the most important things readers will learn about the scientific theory of gearing?

Without going into details I’d say that use of the approach that is disclosed in my book makes it possible to design and manufacture a gear pair, which fits the best to a particular pre-specified application. For the first time ever, the best possible gear pair can be synthesized in order to meet all the pre-specified requirements. The proposed gearing is insensitive to the axis misalignment (it is self-adjustable), and is capable of transmitting the highest possible power density.

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